He was already due to miss the return fixture this weekend but O'Connor revealed that the extent of the injury may give Healy, who was an early casualty of the British & Irish Lions tour with an ankle problem, a race against time for the Six Nations.
"Cian had ankle surgery on Wednesday so he's unavailable for about eight weeks," said O'Connor. "He's doing good but he won't play for a while."
Meanwhile Leinster and Lions teammate Sean O'Brien is also a doubt for the return game with Northampton this weekend after suffering a dead leg.
"Sean trained all right so we'll wait and see. We'll give him as long as possible and hopefully he'll be right," added O'Connor.
"The result was pleasing but the guys are under no illusions about what Saints will bring this week."
Follow us on Facebook, join the conversation on Twitter, sign up to our YouTube channel for extensive match highlights and sign up for our newsletter for regular updates on the RaboDirect PRO12
63x46.png){kind=logo}